Metallic miniaturized hollow shaped bodies and method for producing shaped bodies of this type

Abstract

According to the invention, the shaped bodies are comprised of at least one heavy metal, preferably Fe, Ni, Co, Sn, Mo or W which can be reduced from a corresponding metallic compound at a temperature of less than 1 500° C. The shaped bodies have an outer diameter ranging from 0.05 to 0.5 mm, and a diameter-to-wall thickness ratio of 0.5 to 3%. According to the method, starting materials are deposited as an enveloping layer on supporting elements of any shape, and the green compacts thus produced are subsequently heat-treated. On that occasion, the supporting elements are pyrolyzed, the enveloping layers are essentially thermally decomposed and the decomposition products are sintered. The outer dimensions of the supporting elements are selected such that they are larger than the shaped bodies to be produced. Metallic compounds, preferably metal oxides, metal hydroxides, metal carbonates or organometallic compounds are used as starting materials and can be reduced at a temperature of less than 1 200° C. The thermal treatment is carried out in a reductive atmosphere containing hydrogen and/or carbon such that the starting materials are essentially reduced to the sintered metal which is based on the respectively used metallic compound.

1 . Metallic miniaturized hollow shaped bodies, characterized in that said metallic shaped bodies are comprised of at least one heavy metal which can be reduced from a corresponding metallic compound at a temperature of less than 1 500° C., and that said metallic shaped bodies have an outer diameter ranging from 0.05 to 0.5 mm and a diameter-to-wall thickness ratio ranging from 0.5 to 3%.  
     
     
         2 . Metallic shaped bodies according to  claim 1 , characterized in that said metallic shaped bodies are comprised of at least one heavy metal, which can be reduced from a corresponding metallic compound at a temperature of less than 1 200° C.  
     
     
         3 . Metallic shaped bodies according to  claim 1  or  claim 2 , characterized in that said metallic shaped bodies are comprised of Fe, Ni, Co, Sn, Mo, Cr, Cu, Ag, Pd or W.  
     
     
         4 . Metallic shaped body according to any one of  claims 1  to  3 , characterized in that said metallic shaped bodies are comprised of an alloy.  
     
     
         5 . Metallic shaped bodies according to any one of  claims 1  to  4 , characterized in that the wall of said metallic shaped bodies are formed in a multilayered manner.  
     
     
         6 . Metallic shaped bodies according to any one of  claims 1  to  5 , characterized in that said metallic shaped bodies are sintered to structural members or semifinished products.  
     
     
         7 . A method for the production of metallic miniaturized hollow shaped bodies in which the starting materials are deposited as an enveloping layer upon supporting elements of any shape, said green compacts thus produced are subsequently heat-treated such that said supporting elements are pyrolyzed and said enveloping layers are essentially thermally decomposed, and the decomposition products are sintered, characterized in that supporting elements will be selected which have outer dimensions which are greater than said shaped bodies to be produced, that metallic compounds, preferably metal oxides, metal hydroxides, metal carbonates or organometallic compounds are selected as starting materials and can be reduced at a temperature of less than 1 500° C., and that said green compacts are heat-treated in a reductive atmosphere containing hydrogen and/or carbon such that said metallic compound is essentially reduced to metal, and said metal is sintered.  
     
     
         8 . A method according to  claim 7 , characterized in that metallic compounds are selected which can be reduced at a temperature of less than 1 200° C.  
     
     
         9 . A method according to  claim 8  or  claim 9 , characterized in that as a metallic compound is selected such one which is based on the metals of Fe, Ni, Co, Sn, Mo, Cr, Cu, Ag, Pd or W.  
     
     
         10 . A method according to any one of  claims 7  to  9 , characterized in that at least two metallic compounds forming one metal alloy are selected.  
     
     
         11 . A method according to any one of  claims 7  to  10 , characterized in that powder metallic compound(s) is (are) used.  
     
     
         12 . A method according to any one of  claims 7  to  11 , characterized in that said starting materials are used at least partially in a colloidal form or a dissolved form.  
     
     
         13 . A method according to any one of  claims 7  to  12 , characterized in that said starting materials are deposited in a multilayered manner on said supporting bodies.  
     
     
         14 . A method according to any one of  claims 7  to  13 , characterized in that said thermal treatment of said green compacts is carried out in a mould for the formation of structural members or semifinished structural members.  
     
     
         15 . A method according to any one of  claims 7  to  14 , characterized in that as supporting bodies are selected such ones which have been produced by means of extruders wherein the original extruder castings are subsequently disintegrated.